Industrial drums made of steel and fiberboard are commonly used to transport flowable materials from place to place. When such drums are used without liners, the drums must be cleaned before re-use or disposed of. If a drum is used with a toxic or hazardous material, the disposal of the drum becomes a problem as it cannot simply be placed in normal landfill. Still further, over time, unlined drums are susceptible to corrosion, raising the risk of a spill of the drum's contents.
In order to overcome these problems, both rigid and flexible plastic liners have been proposed. Rigid liners, as described in U.S. Pat. No. 4,712,711, may be used when extremely corrosive or toxic materials are transported and the assembled drum must be able to withstand a substantial drop. Flexible liners may be employed for most other purposes to maintain material away from the internal walls of the drum (See e.g., U.S. Pat. Nos. 4,635,814, 3,409,201, 3,262,628, 3,215,307, 3,167,210 and co-pending applications Ser. Nos. 07/428,469, and 07/428,464).
One important factor in the use of flexible drum liners is the manner in which the liner is mated to a hole ("bung hole") in the lid of the drum. This is because the insertion of the bag in the drum is critical to proper functioning of the package during filling and shipment. Many previous liners have accomplished this mating by using the cap receiving threads common to most bung holes (See e.g. U.S. Pat. No. 2,987,216). With this technique, the liner is subject to twisting in the drum. In order to overcome this problem, a number of fittings which protrude through secondary holes cut in the lid of the drum have been employed (see e.g. U.S. Pat. No. 4,635,814). This requires at least a second seal in the flexible liner and frequently, a second non-vent hole cut into the drum lid. In such systems, the possibility of leaks and/or ruptures is greatly increased.